Fats and oils are essential for a human body as nutrients and source of energy supply (the primary function), and moreover, are important for providing so-called sensory function (the secondary function), which satisfies food preferences, for example, taste or aroma. In addition, fats and oils containing diacylglycerols at a high concentration are known to show physiological effects (the third function) such as body fat-burning effect.
Untreated fats and oils obtained by squeezing seeds, germs, pulp, and the like of plants contain, for example, fatty acids, monoacylglycerols, and odor components. Further, when the untreated fats and oils are processed, trace components are generated as by-products through a heating step such as a transesterification reaction, an esterification reaction, or a hydrogenation treatment, resulting in deterioration of the taste and flavor of the resultant fats and oils. Thus, a process of so-called deodorization, in which the fats and oils are brought into contact with water vapor under a reduced pressure at a high temperature, is generally performed (Patent Document 1).
Further, in order to treat diacylglycerol-rich fats and oils, it is reported to adopt a method involving adding an organic acid to fats and oils rich in diacylglycerols and subsequently carrying out a decoloration treatment and a deodorization treatment with a porous adsorbent, so as to provide good taste and flavor (Patent Document 2), or a method involving carrying out an esterification reaction between glycerin and each of fatty acids obtained by hydrolyzing raw material fats and oils by an enzymatic decomposition method and subsequently carrying out a deodorization treatment so that a deodorization time and a deodorization temperature can be each controlled in a given range (Patent Document 3).